FIG. 1 illustrates a body lock ring 10 positioned outside a mandrel 12 with an outer housing 14 surrounding the lock ring 10. Arrow 16 indicates an applied force to the outer housing 14 with the mandrel 12 held fixed. In that situation the housing 14 can move down in the direction of arrow 16 and take the lock ring 10 with it. This is because the thread 18 orientation with respect to the orientation of thread 20 on the lock ring 10 is such that in the direction on movement of housing 14 indicated by arrow 16 the threads 18 and 20 are oriented for only tandem movement without ratcheting over each other. However, thread 22 on the opposite side of the lock ring 10 from thread 20 is oriented with respect to thread 24 on the mandrel 12 so that tandem motion of the housing 14 with the lock ring 10 can take place because the thread 22 ratchets over thread 24 using the clearance space 26 available on opposed sides of the lock ring 10 to allow the actuation of the tool with the force in the direction of arrow 16. Such a force and a movement of the housing 14 can be used for example to set slips and sealing elements on a packer or bridge plug or open or close a port as some possible examples. The point being that the lock ring 10 allows relative movement in one direction and locks in that movement in the opposite direction. This locking feature is seen in FIG. 2 where after setting and removing the setting force represented by arrow 16 there is a reaction force in the opposite direction of arrow 28. Now thread 18 drives thread 20 for tandem attempted movement in the direction of arrow 28 but this movement is stopped by the inability of thread 22 to ratchet over thread 24 when the lock ring 10 is pushed in the direction of arrow 28. Normally, this locked position is held. If it is desired to remove the tool such as a packer or a bridge plug, then the tool can be milled out or its mandrel cut into pieces to relieve the grip of lock ring 10.
In one prior design the lock ring is held in an operating position to ratchet lock and is released when a surrounding sleeve held in position by a lock ring which when undermined by sleeve movement allows a release of the lock ring assembly 42,302 and 312 for a release of the ratchet as shown when comparing FIGS. 14 and 23 of U.S. Pat. No. 5,595,247. This patent was reissued as RE 36,526 and has a related case of U.S. Pat. No. 4,898,245.
Other designs features lock segments that hold two members together until the segments have support removed that allows separation of the two members that were formerly held together. Some examples of such designs are items 40 and 62 in FIG. 15b of U.S. Pat. No. 4,530,398; items 42 and 100 in FIG. 1 of U.S. Pat. No. 4,614,233; items 142, 144 and 136 in FIG. 4 of U.S. Pat. No. 4,862,957 which has a related case of U.S. Pat. No. 4,660,637.
The present invention addresses this issue with a design that allows a split housing to spring outwardly into a recess that is presented opposite the split housing as the setting sleeve is picked up. The housing has the ability to use the locked in spring force to get into the recess far enough so that the gripping teeth on the housing retreat sufficiently from the lock ring to unset the tool and remove it from a subterranean location. This can be done while avoiding damage to the major components. These and other features of the present invention will be better understood by those skilled in the art by a review of the description of the preferred embodiment and the associated drawings while understanding that the full scope of the invention is to be found in the appended claims.